NEETZoologyNeural Control and Coordination
What makes neurons excitable cells?
Options
- ATheir membranes are polarised.
- BTheir membranes are non-polarised.
- CTheir membranes are partially polarised.
- DTheir membranes are impermeable to ions.
Correct answer
A. Their membranes are polarised.
Step-by-step solution
The outer surface of the axonal membrane possesses a positive charge while its inner surface becomes negatively charged and therefore is polarised The sodium-potassium pump transports 3 Na⁺ ions outwards for 2 K⁺ ions into the cell.When a neuron is resting, the axonal membrane is more permeable to potassium ions (K⁺) and nearly impermeable to sodium ions (Na⁺). The axoplasm inside the axon contains high concentration of K⁺ and low concentration of Na⁺. The resting potential of the plasma membrane of a neuron is the